This is the proportion of our distribution of sample means that falls into the critical regions.

Folstein and Rutter studied sets of identical twins in which only one child was autistic. What did they find to be associated with autism of the affected child?

a) inheritance of a recessive trait b) brain injury at or just after birth c) immunological rejection in utero d) infection that passed the placenta

In early elementary school in the United States, understanding math principles such as fractions and the place value concept has been found to benefit the most from which of the following teaching strategies?

a. Using concrete aids such as a place value board b. Having children memorize solutions to problems by rote as teachers do in Korea c. Presenting the problems in the form of word problems d. Teaching children the metric system first, and then the concept of place value